IMPROVEMENTS IN OR RELATING TO A SHEET OFFSET PRESS

Abstract: The invention relates to an apparatus for offset presses, and includes an air-IR drying box (1), through which ready-printed sheets (2) are caused to be conveyed with the aid of gripping means (3), for the purpose of drying pigment deposited on the sheets. The box (1) has screening means along gaps (4, 5) delimiting it laterally, the screening means being implemented as at least one brush means (6) having brush material (8-11) covering the gaps (4, 5) and extending perpendicularly to the conveying direction (7) for preventing the spread of heat radiation and hot air from the IR lamps (12) in the box (1) to different machine parts of the press.

Description: IMPROVEMENTS IN OR RELATING TO A SHEET OFFSET PRESS The present invention relates to an apparatus for offset presses and includes an air-infra-red (IR) drying box, through which ready-printed sheets are caused to be conveyed with the aid of gripping means, for the purpose of drying pigment deposited on the sheets. A continually recurring problem with the installation of IR drying boxes in offset presses is that the IR lamps radiate to some extent heat up metallic parts of the press, including its frame sides and the gripping means conveying the sheets. Several attempts have al- ready been made to screen off the IR lamps, but the problem lies with the gripping means that have to pass the place where the box is mounted. The object of the present invention is to achieve an effective heat barrier in offset presses, the barrier allowing the gripping means to pass while at the same time preventing the heat radiation from the IR lamps from spreading to the different machine parts of the press. The distinguishing features of the invention are disclosed in the accompanying claims. Due to the present invention there has now been achi¬ eved an effective heat barrier in offset presses of the kind mentioned in the introduction, the barrier ful- filling its purpose in an excellent manner, while at the same time it is both simple and cheap to manufact¬ ure, as well as easy to fit. The inventive heat barrier comprises heat resistant brush material arranged at the gaps laterally delimiting an air-IR drying box and its IR lamps, this box being mounted on an offset press. This brush material is made from a heat-resisting sub¬ stance, which is also heat-insulating and flexible. It is therefore possible to mount and adjust mutually opposing lengths of the brush material such as to comp¬ letely cover the gaps laterally delimiting the box, while allowing passage of gripping means through it, since filaments of brush material will be deflected as respective portions of the gripping means come into contact with them, and will return immediately to their original attitudes after passage of the gripping means. The brush material does not cause any damage to the portions of the gripping means with which it engages, and it can be supplied with relatively long brush fila¬ ments that can be trimmed to a suitable length on in¬ stallation. In addition, a brush comprising the brush material may be fastened to a rail, which is flexible in the conveying direction of the sheets, curved guides used with the gripping means thus not causing any prob¬ lem. The invention will now be described in more detail with the aid of a preferred embodiment example and with reference to the accompanying drawing, which depicts a schematic, perspective view of an air-IR drying box installed on an offset press. As will be seen from the drawing, the air-IR drying box 1, intended for mounting on an offset press, is adapted to accept ready-printed sheets 2 for drying the pigment deposited thereon, these sheets being conveyed with the aid of gripping means 3. IR lamps 12 are mounted in the box 1 in given, spaced relationship, and in the illu- strated example, in the conveying direction of the sheets 2. The gaps 4 and 5 laterally delimiting the box 1 are each screened by at least brush means 6 extending in the conveying direction 7 of the sheets 2 and comp¬ rising respective brush material 8, 9 and 10, 11 for closing off the respective gap and preventing the spread of IR radiation and hot air generated by the IR lamps in the box 1 to different components of the off¬ set press. According to the preferred embodiment example depicted on the drawing, the laterally delimiting gaps 4 and 5 between the respective side elements are each screened off by brush means 6 extending in the conveying direc- tion. The brush material 8-11 of the means 6 is both heat-resistant and heal-insulating, as well as having a flexibility permitting the gripping means 3 to pass. The filaments in the respective mutually opposed brush means 6 have their outer, free portions 15, 15', 16, 16', mutually, opposingly directed and preferably ex¬ tend completely across the gaps 4 and 5 such as effec¬ tively to close off the gaps. These outer free portions 15; 15'; 16; 16' of the respective brush material 8-11 are mutually contiguous along a line 23, which is at the same level as the central point of, and conveying path for the portions 13, 14 of a gripping means 3, these portions being intended to be taken through, bet¬ ween and along brush means 6 as the gripping means 3 is advanced through the air-IR drying box 1. The outer free portion of the brush material 8-11 of the respec¬ tive brush means 6 preferably extends over the entire gaps 4 and 5 both from above and below such as to meet along the middle of the respective gap. To enable the use of curved gripping means guides the brush material 8-11 may be fastened to a rail, which is flexible in the sheet conveying direction 7. By reason of the great flexibility of the brush material 8-11 it is possible to adjust it so that opposing filaments touch a passing gripping means 3, merely deflecting the filaments until it passes between them, subsequent to which they imme¬ diately return to their original attitudes. The brush material can be delivered with relatively long fila¬ ments, for clipping to appropriate length on installa¬ tion. The preferred embodiment of the air-IR box 1 illustrated on the drawing includes an upper, water- cooled reflector 17, having connections 18, 19 for cooling water. The lower part of the box 1 includes an IR lamp array 20, and in the illustrated embodiment cold air, via connections 21 and 22, is used to cool it. It is of course also possible to an inverted set-up with the reflector 17 below and the array 20 above, such as to obtain fully effective function.

Claims: Claims 1. Apparatus for offset presses, comprising an air- infra-red (IR) drying box (1) , through which ready- printed sheets (2) are arranged for conveyance with the aid of gripping means (3) for drying pigments deposited on the sheets, characterized in that the box (1) has screening means along gaps (4, 5) delimiting it later¬ ally, said screening means being implemented as at least one brush means (6) having brush material (8-11) covering said gaps and extending perpendicularly to the conveying directing (7) of the sheets 2, such as to prevent the spread of heat radiation and hot air gene¬ rated by IR lamps 12 in the box (1) to different mach- ine parts of the press. 2. Apparatus as claimed in claim 1, characterized in that the brush material (8-11) of the brush means (6) is both heat-insulating and heat-resistant as well as possessing a flexibility, which permits the gripping means (3) to pass. 3. Apparatus as claimed in claim 1, characterized in that the respective gap (4, 5) laterally delimiting the box 1 is provided with two opposing brush means (6) , the respective brush material (8, 9; 10, 11) of which has its free outer portion (15, 15'; 16, 16') directed towards the corresponding free outer portion of the contiguous brush material, these opposing brush mate- rial filaments preferably extending completely over said gaps (4, 5) to cover them. 4. Apparatus as claimed in claim 3, characterized in that the outer free end portions (15; 15'; 16, 16') of the respective brush material are mutually contiguous along a line 23, which is at the same level as the central line of, and conveying path for the portions (13, 14) of a gripping means (3), these portions being intended to be taken through, between and along the brush means (6) as the gripping means 3 is advanced through the air-IR drying box 1. 5. Apparatus as claimed in claim 3, characterized in that the outer free end portions (15, 15'; 16, 16') of the brush material (8-11) pertaining to the respective brush means 6 extend over the entire height of the gaps (4, 5) delimiting the box 1 laterally, both from above and below such as to meet along the middle of the gaps. 6. Apparatus as claimed in any one of the preceding claims, characterized in that the brush material (8-11) is fastened to a rail, which is flexible in the convey- ing direction of the sheets.

Inventors: PETTERSSON KJELL, PETTERSSON, KJELL
Applicants: ACROTEC AB, PETTERSSON KJELL, PETTERSSON, KJELL
Application year: 1994
Main classification: B41F23
IPC codes: B41F23